PRAGMATIC VERSUS EXPLANATORY TRIALS - THE DUALISM

A comparative clinical trial may have different objectives. For instance, it may be aimed at finding out whether a new drug is actually efficient in man, as suggested by the results of experimental studies: this occur when new molecules are found, or when new indications are discovered for an old drug. In such cases clinical trials are designed as laboratory experiments and the drug must be used in optimum conditions so that its efficacy can be best proven. The trial is said to have an explicative design. A different objective for a trial may be to evaluate the practical interests of a new treatment, the efficacy of which has already been proven; this treatment will then be compared to those already existing and its advantages as well as its drawbacks will have to be considered when recommendations are given. This approach requires a pragmatic design, in order to help physicians take the best therapeutic decisions (or society to take public health decisions). Finally, it is the experimental or pragmatic design of a trial which determines the choice of patients, endpoint criteria, drug regimen, follow-up and methods of comparison.